Degaussing　used　magnetic　hard　drives　is　a　common　means　of　destroying　magnetic　information.　Customized　degaussing　for　different　magnetic　hard　drives　can　improve　the　efficiency　of　magnetic　information　destruction.　In　this　scenario,　it　is　necessary　to　quickly　identify　the　used　magnetic　hard　disk　firstly.　Aim　at　the　above　problem,　this　paper　proposes　to　apply　machine　vision　to　the　identification　of　magnetic　hard　disk　serial　number.　At　first,　the　magnetic　hard　disk　serial　number　image　is　preprocessed.　Then,　the　serial　number　is　segmented　and　its　HOG　features　are　extracted.　Finally,　a　support　vector　machine　(SVM)　algorithm　is　used　to　construct　a　recognition　model.　The　effectiveness　of　the　proposed　method　is　verified　by　the　magnetic　hard　disk　serial　number　image.